Infectious Diseases Endangering Amphibians

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The emergences of infectious diseases represent one of the greatest threats confronting amphibians. One third of the world’s amphibian population is facing extinction. Frog populations have also been steadily declining. Amphibian populations are faced with invasive environmental problems including infectious diseases. (Holland et al. 2007). Ribeiroia ondatrae, a trematode parasite, is suggested to be linked to the rise in frog mutations during development. Mutations include: missing, extra, and/or malformed limbs.
Environmental change mediated by humans is recognized as a leading cause of both human and wildlife emerging infectious diseases (Gratz et al 2001) Eutrophication, due to agriculture, livestock, sewage waste, and erosion, is one form of anthropogenic change that is being incriminated in its role in disease emergence. Riberoia ondatrae has been linked to the increase in the concentration of phosphorus, nitrogen, and other plant nutrients in an aging aquatic ecosystem. Eutrophication is affecting the amphibian lifespan by increasing the density of snail hosts. An experiment conducted by Johnson et al. (2007) suggested that eutrophication promoted parasite infections because the increase in resource availability increased the population growth of snail hosts, leading to a heightened parasite transmission and a higher density of infected snails.
Ribeiroia ondatrae, which infects freshwater snails, larval amphibians, and water birds, has been causally linked to high frequencies of malformations (10–90%) in amphibian populations. (Johnson et al. 2007) Evidence suggests that metacercariae infection is responsible for mutations among frog species. Johnson et al. (2002) summarized the basic life cycle of Ribeiroia ondatr...

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